Backport #22019
Although there are per-locale fallbacks for ambiguity the locale names
for Chinese do not quite match our locales. This PR simply maps zh-CN on
to zh-hans and other zh variants on to zh-hant.
Ref #20999
Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: Lauris BH <lauris@nix.lv>
This PR rewrites the invisible unicode detection algorithm to more
closely match that of the Monaco editor on the system. It provides a
technique for detecting ambiguous characters and relaxes the detection
of combining marks.
Control characters are in addition detected as invisible in this
implementation whereas they are not on monaco but this is related to
font issues.
Close#19913
Signed-off-by: Andrew Thornton <art27@cantab.net>
